The relevance of biologically effective dose for pain relief and sensory dysfunction after Gamma Knife radiosurgery for trigeminal neuralgia: an 871-patient multicenter study.

OBJECTIVE: Recent studies have suggested that biologically effective dose (BED) is an important correlate of pain relief and sensory dysfunction after Gamma Knife radiosurgery (GKRS) for trigeminal neuralgia (TN). The goal of this study was to determine if BED is superior to prescription dose in predicting outcomes in TN patients undergoing GKRS as a first procedure. METHODS: This was a retrospective study of 871 patients with type 1 TN from 13 GKRS centers. Patient demographics, pain characteristics, treatment parameters, and outcomes were reviewed. BED was compared with prescription dose and other dosimetric factors for their predictive value. RESULTS: The median age of the patients was 68 years, and 60% were female. Nearly 70% of patients experienced pain in the V2 and/or V3 dermatomes, predominantly on the right side (60%). Most patients had modified BNI Pain Intensity Scale grade IV or V pain (89.2%) and were taking 1 or 2 pain medications (74.1%). The median prescription dose was 80 Gy (range 62.5-95 Gy). The proximal trigeminal nerve was targeted in 77.9% of cases, and the median follow-up was 21 months (range 6-156 months). Initial pain relief (modified BNI Pain Intensity Scale grades I-IIIa) was noted in 81.8% of evaluable patients at a median of 30 days. Of 709 patients who achieved initial pain relief, 42.3% experienced at least one pain recurrence after GKRS at a median of 44 months, with 49.0% of these patients undergoing a second procedure. New-onset facial numbness occurred in 25.3% of patients after a median of 8 months. Age ≥ 63 years was associated with a higher probability of both initial pain relief and maintaining pain relief. A distal target location was associated with a higher probability of initial and long-term pain relief, but also a higher incidence of sensory dysfunction. BED ≥ 2100 Gy2.47 was predictive of pain relief at 30 days and 1 year for the distal target, whereas physical dose ≥ 85 Gy was significant for the proximal target, but the restricted range of BED values in this subgroup could be a confounding factor. A maximum brainstem point dose ≥ 29.5 Gy was associated with a higher probability of bothersome facial numbness. CONCLUSIONS: BED and physical dose were both predictive of pain relief and could be used as treatment planning goals for distal and proximal targets, respectively, while considering maximum brainstem point dose < 29.5 Gy as a potential constraint for bothersome numbness.

The effect of tumor shape irregularity on Gamma Knife treatment plan quality and treatment outcome: an analysis of 234 vestibular schwannomas.

The primary aim of Gamma Knife (GK) radiosurgery is to deliver high-dose radiation precisely to a target while conforming to the target shape. In this study, the effects of tumor shape irregularity (TSI) on GK dose-plan quality and treatment outcomes were analyzed in 234 vestibular schwannomas. TSI was quantified using seven different metrics including volumetric index of sphericity (VioS). GK treatment plans were created on a single GK-Perfexion/ICON platform. The plan quality was measured using selectivity index (SI), gradient index (GI), Paddick's conformity index (PCI), and efficiency index (EI). Correlation and linear regression analyses were conducted between shape irregularity features and dose plan indices. Machine learning was employed to identify the shape feature that predicted dose plan quality most effectively. The treatment outcome analysis including tumor growth control and serviceable hearing preservation at 2 years, were conducted using Cox regression analyses. All TSI features correlated significantly with the dose plan indices (P < 0.0012). With increasing tumor volume, vestibular schwannomas became more spherical (P < 0.05) and the dose plan indices varied significantly between tumor volume subgroups (P < 0.001 and P < 0.01). VioS was the most effective predictor of GK indices (P < 0.001) and we obtained 89.36% accuracy (79.17% sensitivity and 100% specificity) for predicting PCI. Our results indicated that TSI had significant effects on the plan quality however did not adversely affect treatment outcomes.

Psychiatrist decision-making towards prescribing benzodiazepines: the dilemma with substance abusers.

Psychiatrists' decision making about prescribing benzodiazepines (BZD) was evaluated in a community mental health center. An anonymous survey of outpatient psychiatrists in an academic-affiliated public mental health center was conducted using a 45-item questionnaire developed based on the results of a previous study. Sixty-six percent of responses indicate that, at times, psychiatrists experienced requests for behaviors suspicious for abuse, including 'lost/missing prescriptions' and 'use of BZD by others'. Patient characteristics such as 'history of abuse', 'unknown patient', and 'patient use of illicit substances' were occasional or common reasons for NOT prescribing BZDs (75%). The most common contexts in which the majority of our sample was uncomfortable prescribing BZDs involved a patient history of substance abuse, fear of initiation of dependence, diversion, and feeling manipulated by the patient. Time limitations were a dilemma for 20%. Psychiatrist self-reported dilemma and behavior in prescribing BZDs largely reflected concerns with substance abuse and less frequently workload or time issues.

A preliminary investigation of varenicline for heavy drinking smokers.

RATIONALE: Varenicline, an approved smoking cessation pharmacotherapy, also shows promise as a potential treatment for alcohol dependence. However, varenicline has not been tested in heavy drinkers, and it remains to be determined whether varenicline could reduce alcohol craving and consumption in smokers who are trying to quit smoking. OBJECTIVES: We conducted a preliminary study to examine the effect of varenicline on drinking behavior and the effects of extended varenicline pretreatment on smoking. METHODS: Thirty heavy drinking smokers received smoking cessation counseling and were randomly assigned to receive either an extended 4-week pretreatment with varenicline 2 mg daily or the usual 1-week pretreatment. Those in the extended pretreatment group received active medication for 8 weeks (i.e., 4 weeks of active pre-treatment followed by 4 weeks of active treatment), and participants in the usual pretreatment group received active medication after a placebo lead in (i.e., 3 weeks of placebo followed by active medication for 5 weeks). RESULTS: Participants who received varenicline during the first 3 weeks reported significantly greater reductions in alcohol craving and numerically fewer heavy drinking days compared to those who received placebo, and these differences persisted during the open-label phase. Extended pretreatment was associated with numerically greater reductions in cigarette smoking over the entire study period. There were no differences, however, in smoking abstinence rates following the smoking quit date between the two groups. CONCLUSIONS: Findings from this preliminary study suggest that varenicline may be a promising strategy for concurrently reducing heavy drinking and promoting smoking changes in heavy drinkers.